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Shermann

Odd problems on V SPEED

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Hi everyone,

 

Lately i installed a livery form the OP. The livery is Aerologic ( ithink not the one form PMDG but one form avsim). Well during preflight i set all the FMC as usuall inserting the route runway in use SId start arrival runway and so on set the flex temp the flap to use and i was waiting for the allignment. After the FMC was alligned i had a message on the FMC refering the V spped were not aviable. I was thinking well it is not important i insert them by hand but actually any kind of speed i add i received an Invalid format or something like this message. What can cause the problem?

To inset the speed manually i even tried to set the selct ref speed to OFF but nothing i put it back to on delete the value of flaps and flex tremp but again no speed aviable  so i had to take off without setting the v speeds.

 

What o wopder is , can a single livery cause the problem?  and if yes what can cause it, if not why the FMC didnt calculate the V-Speeds?  All discontinuity were eliminated weight were set ZFW and fuel. Cost index winds. temperature at cruise altitude.Sid and star runway in use wind for the runway accelration point and reduction altitude. I even tried to eliminate the flex temp thinking maybe the plane was not able to take off in flex temp. Was a flight from europe to thailand so i was thinking maybe the weight is too high and Flex temp is not allowed but nothing.

 

 

Thanks to Everyone

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I only got NO V SPEED AVAILABLE message once, and that was because i apparently entered too high assumed temperature and derate for the weight. So try selecting another derate or lower the assumed temperature.

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Setting an assumed temp of zero would not cancel it, in fact it would probably confuse things further. Either deleting it completely or entering the SAT as the assumed temp would work.

 

Btw, what was the original assumed temp entered? It should always be higher then the current SAT

 

Regards

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the original assumed temperature was 33 degrees. And i didnt set it to zero  pressed DEL button and then LSK1. Runway is 26L EDDP 3600 meter long. Temperature was 11 degrees. ZFW was 187000 KG FUEL was 105000 KG.

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Sorry for the length of post but have a read of this, see if it helps...

 

 

V–SPEEDS UNAVAILABLE – For certain high thrust/low gross weight takeoff conditions, FMC V–speeds are not calculated. Adjust gross weight and/or takeoff thrust limit to enable V–speed calculations.

 

The FMC will protect for minimum control speeds by increasing V1, VR and V2 as required.

 

However, the FMC will not compute takeoff speeds for weights where the required speed increase exceeds the maximum certified speed increase.

 

This typically occurs at full rated thrust and light weights.

 

In this case, the message "V SPEEDS UNAVAILABLE" will appear on the FMC scratchpad and the takeoff speed entries will be blank.

 

Takeoff is not permitted in this condition as certified limits have been exceeded.

 

The options are to select a smaller flap setting, select derate thrust and/or add weight (fuel).

 

Selecting derate thrust is the preferred method as this will reduce the minimum control speeds.

 

Note that the assumed temperature method may not help this condition as the minimum control speeds are determined at the actual temperature and therefore are not reduced.

 

Incase of 777-200 LR: The FMC will not compute takeoff speeds for weights below those shown in the Minimum Weight for FMC Takeoff Speeds Calculation table.

 

In those cases where the required speed increase exceeds the maximum speed increase built into the FMC, the message "V SPEEDS UNAVAILABLE" will appear on the FMC scratchpad and the takeoff speed entries will be blank. This typically occurs at high rated thrust, high flaps setting and light weights.

 

To obtain speeds for the takeoff in these situations, the options are to use available performance software, or select a smaller flaps setting, or use reduced takeoff thrust and/or add weight.

  • Upvote 1

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INteresting very interesting! But in my case i dont know what caused the problems. IF i understood right i should have put a derated teperature that is higher or lowe the flap setting. Flap setting was 5 and derated temperature was 33. Anyway i am sure the probem is about what u posted. So thanks again.

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Sorry for the length of post but have a read of this, see if it helps...

 

I think if anyone needs to apologize about the length of posts around here...haha.

 

Good read, though.

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INteresting very interesting! But in my case i dont know what caused the problems. IF i understood right i should have put a derated teperature that is higher or lowe the flap setting. Flap setting was 5 and derated temperature was 33.

 

Alfredo,

 

I think what Rob is saying is NOT to use an assumed temperature, but to use a fixed derate instead.

 

Thanks Rob for your post!

 

Mike

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Hi everyone,

 

Lately i installed a livery form the OP. The livery is Aerologic

So do you only have this problem with the Aerologic livery or with all liveries?

 

And is this problem reproduceable or was it a one time thing?

 

 

EDIT: disregard, it seems yu have solved you problem according post #7

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I had this problem and found that my spoilers were deployed because my controllers were applying very slight reverse thrust while sitting at the gate (with the hydraulics on).  Returning the thrust to idle, and stowing the spoilers allowed me to enter the data appropriately.

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